The present invention relates to the field of mass storage devices. More particularly, this invention relates to stepped disc drive voice coil actuator acceleration for reducing resonance or ringing of head level micro-actuators for a mass storage device.
One key component of any computer system is a device to store data. Computer systems have many different places where data can be stored. One common place for storing massive amounts of data in a computer system is on a disc drive. The most basic parts of a disc drive are a disc that is rotated, an actuator that moves a transducer to various locations over the disc, and electrical circuitry that is used to write and read data to and from the disc. The disc drive also includes circuitry for encoding data so that it can be successfully retrieved and written to the disc surface. A microprocessor controls most of the operations of the disc drive as well as passing the data back to the requesting computer and taking data from a requesting computer for storing to the disc.
The transducer is typically placed on a small ceramic block, also referred to as a slider, which is aerodynamically designed so that it flies over the disc. The slider is passed over the disc in a transducing relationship with the disc. Most sliders have an air-bearing surface (xe2x80x9cABSxe2x80x9d) which includes rails and a cavity between the rails. When the disc rotates, air is dragged between the rails and the disc surface causing pressure, which forces the head away from the disc. At the same time, the air rushing past the cavity or depression in the air bearing surface produces a negative pressure area. The negative pressure or suction counteracts the pressure produced at the rails. The slider is also attached to a load spring that produces a force on the slider directed toward the disc surface. The various forces equilibrate so the slider flies over the surface of the disc at a particular desired fly height. The fly height is the distance between the disc surface and the transducing head, which is typically the thickness of the air lubrication film. This film eliminates the friction and resulting wear that would occur if the transducing head and disc were in mechanical contact during disc rotation. In some disc drives, the slider passes through a layer of lubricant rather than flying over the surface of the disc.
Information representative of data is stored on the surface of the storage disc. Disc drive systems read and write information stored on tracks on storage discs. Transducers, in the form of read/write heads attached to the sliders, located on both sides of the storage disc, read and write information on the storage discs when the transducers are accurately positioned over one of the designated tracks on the surface of the storage disc. The transducer is also said to be moved to a target track. As the storage disc spins and the read/write head is accurately positioned above a target track, the read/write head can store data onto a track by writing information representative of data onto the storage disc. Similarly, reading data on a storage disc is accomplished by positioning the read/write head above a target track and reading the stored material on the storage disc. To write on or read from different tracks, the read/write head is moved radially across the tracks to a selected target track. The data is divided or grouped together on the tracks. In some disc drives, the tracks are a multiplicity of concentric circular tracks. In other disc drives, a continuous spiral is one track on one side of a disc drive. Servo feedback information is used to accurately locate the transducer. The actuator assembly is moved to the required position and held very accurately during a read or write operation using the servo information.
Increasing demand for data density makes higher track densities imperative. There is also demand for increased access speed, requiring very fast seek speeds. Some disc drives include micro-actuators to allow for fine track-to-track movements. The micro-actuator is an additional actuator located between the suspension and the slider of the head gimbal assembly (HGA) to provide minor positioning adjustments.
The micro-actuator may consist of a stationary part or xe2x80x9cstator portionxe2x80x9d attached to the suspension gimbal and a moving part or xe2x80x9crotor portionxe2x80x9d that carries the read write head. The stator portion and rotor portion are connected with thin beams that act as springs, allowing enough movement to center the head on a very narrow track or switch between adjacent tracks.
However, high speed data access requires abrupt acceleration and de-acceleration of the micro-actuator. This sharp motion causes the rotor portion to resonate or vibrate at its natural frequency. This natural ringing can significantly impact the ability to obtain acceptable seek times since the micro-actuator does not settle or stop ringing at the end of a seek operation.
What is needed is a disc drive that reduces resonance of head level micro-actuators for a mass storage device.
The present invention provides stepped disc drive voice coil actuator acceleration for reducing ringing or resonance of head level micro-actuators for a mass storage device.
One embodiment includes a disc drive having a voice coil actuator with an attached suspension and head, the head including a micro-actuator. The micro-actuator having at least one natural frequency and at least one natural frequency time period. The voice coil actuator is adapted to attenuate a resonance of the micro-actuator at the at least one natural frequency using a stepped acceleration.
One embodiment includes a disc drive including a suspension attached to a voice coil actuator with a head attached to the suspension. The head includes a micro-actuator having a rotor portion and a stator portion with the stator portion attached to the suspension. The rotor portion is attached to the stator portion with the rotor portion having a resonance at a natural frequency with respect to the stator portion and having a natural frequency time period. The voice coil actuator is adapted to sweep the head into position by accelerating and decelerating the head in at least three steps.
One embodiment includes a method for damping a micro-actuator including providing a disc drive with a voice coil actuator and a micro-actuator, the micro-actuator having a natural frequency and a natural frequency time period, and applying a stepped acceleration to the micro-actuator with the voice coil actuator.
One embodiment includes an information system including a disc drive having a stepped disc drive voice coil actuator acceleration for reducing ringing of head level micro-actuators for a mass storage device.
The present invention provides stepped disc drive voice coil actuator acceleration for reducing ringing or resonance of head level micro-actuators for a mass storage device. In addition, the present invention provides overall more accurate and faster access times with better reliability.